Desmoplastic melanoma: a 12-year experience with sentinel lymph node biopsy

Given the paucity of data regarding nodal involvement in desmoplastic melanoma (DM), we decided to review the incidence of nodal metastasis in our patients with DM to better define guidelines regarding the performance of sentinel lymph node biopsy (SLNB) in this specific melanoma subtype.

Using a prospectively maintained database, we reviewed all patients who underwent treatment for melanoma at the Yale Melanoma Unit in a twelve-year period (1998-2010), during which 3531 cases were treated. We identified 24 patients (0.7%) diagnosed with DM. These patients' records were studied for clinical and histologic parameters and clinical outcomes.

Twenty-two patients from the DM group had SLNB, of which four (18%) were diagnosed with micro-metastasis. These four patients were all treated with completion lymphadenectomy and none had additional positive nodes in the remainder of the nodes. Patients were followed after surgery for a median of 25 months (range 2-60 months). Two patients (9%) developed local recurrence, two (9%) in-transit recurrence, and six (27%) showed distant metastases (three patients were pure DM and three patients showed mixed morphology). Patients with mixed DM had a higher rate of nodal metastasis (25%) vs those with pure DM (14%).

Other authors have reported that patients diagnosed with pure DM were less likely to have a positive SLN (0-2%) than those patients with the mixed DM subtype (12-16%). Our findings of higher incidence rates of regional lymph node metastases in both the pure and mixed DM subtypes (14% and 25%) compel us to continue to still recommend that SLNB be considered in patients with both subcategories, pure and mixed DM.

Level IV.